Circuit breaker



April 3, 1945. H. c. GRAVES, JR

CIRCUIT BREAKER Filed April 27, 1940 5 Sheets-Sheet l INVENTORY A'i'TORNEY.

m 5 V A R a. c T. R E: B m

April 3, 1945. H. GRAVES, JR

CIRCUIT BREAKER 5 Sheets-Sheet 2 ITTIIT Filed April 7 1940 V INVEINI'ORHERBERT c .eRAvEs,JR.,

AT To RNEY April 3, 1945.

H. C. GRAVES, JR

CIRCUIT BREAKER 5 Sheets-Sheet 3 Filed April 27, 1940 lNVEN'TOR HERBERTC. GRAVES, JR.

ATTORNEY- April 3, 1945.

H. c. GRAVES, JR

CIRCUIT BREAKER 'Filed April 27, 1940 5 Sheets-Sheet 4 INVENTOR HERBERTC-GRAVES,JR.,

ATTOR NEY.

April 3, 1945. E H. c; GRAVES, JR 2,372,773

I CIRCUIT BREAKER Filed April 27, 1940 5 Sheets-Sheet 5 INVENTEDRHERBERT c .GRAVES, JR.,

ATTORNEY.

Patented Apr. 3, 1945 Herbert G. Graves, In, West Chester, Pa., assignorto I.-T.-E. Circuit Breaker Company, Philadelphia, Pa., a corporation ofPennsylvania Application April 27, 1940, Serial No. 331,982

7 Claims.

This invention relates to switch gear and circuit breakers, andvmore'particularly to a panel type combination switch and circuitbreaker adapted for use in branch circuits of various types and arrangedto be mounted upon a panel board together with other similar devices forcontrolling a plurality of circuits.

In the operation of branch circuits, it is frequently important toconnect or disconnect individual circuits from the main line withoutinterfering with the operation of other similar circuits, and toarrangefor overload protection for individual circuits so that in the event ofany fault in any particular branch, that particular circuit mayautomatically be disconnected without interfering in any way with theoperation of other circuits or with the operation of the main circuititself.

Thus, in the operation of a plurality of small motors for variouspurposes in a shop, it is important that any fault occurring in thecircuit to a particular motor should not affect the opera.- tion ofother motors or the main line to the end that continuous operationshould as far as possibie be maintained. 4

Likewise, in the operation of multiple dwellings or apartment houseswhere a plurality of individual circuits for different apartments areall connected to a single main line, it'isimportant that any particularcircuit to any particular apartment be readily connectible to anddisconnectible from the mainline and that any fault in any particularcircuit should not disturb the operation of any of the other circuits.

Accordingly, the purpose and object of the present invention is toprovide a simple combination on-ofi switch and circuit breaker which maybe mounted upon a panel board and connected between the main bus and theindividual branch circuits in order to provide suitable manual orautomatic control for each of the individual circuits.

In order to provide for'panel board mounting of this type and in orderfurther to provide for simplicity in operation and assembly and tofacilitate mounting upon the panel board, it is important that theparticular combination switch and circuit breaker be compact andnevertheless so arranged as to obviate any internal faults or shortcircuits.

Therefore, instead of providing for the creation of a simple' air-gapbetween the movable contact member and the stationary contact member ofthe on-off" switch circuit breaker combination, one of the importantobjects of the present invention is to provide for the interposition oran actual physical dielectric barrier between the two contacts when thecontacts separate.

-Still another extremely important object of the present invention is toso arrange the stationary and movable contacts that they are separatednot by any operation initially performed upon the movable contactitself, but by the sweeping or swinging of the physical barrier ofdielectric material toward circuit opening position. In such case, thebarrier may swing beneath a bearing on the movable contact arm. raisingthe arm, and separating the contacts, and then the barrier by continuingthe movement reaches its final position between' -theseparated-contacts.

The movable contact should therefore be so arranged that it is biasedinto contactingposltion with the stationary contact in such manner thatupon removal of the physical barrier of dielectric material the biasingmeans wi l immediately re-establish contact pressure between the movableand stationary contacts.

Still another object of the present invention is to provide forindividual and separate physical barriers for each of the two operationof crap nary manual switching and automatic switching. That is, onebarrier of dielectric material hereinafter referred to as an interposermay be placed between the contacts by manual operation and another suchinterposer may be interposed between the movable and stationary contactsby automatic circuit breaking means. Both of these barriers may operatein a single plane and it is still another object of the presentinvention to utilize the manually operated interposer or barrier toremove the automatically operated interposer or barrier from between thecontacts when it is desired to reset the switch and circuit breakerafter an automatic tripping thereof.

The circuits and apparatus may be designed to carry (a) a maximumcurrent above and below which small variation may occur, (b) a heavymomentary inrush current as in thermal devices such as lamps whereoperating resistance increases after being switched on, (0) startingcurrents for motors, (it) short periods such as may occur in motors.

When these momentary increases occur, the length of time they lastshould be limited by the circuit breaker preferably in accordance withthe invention provides for an instantaneous trip mechanism forimmediately separating the contacts. Where afault occurs however whichis not suflicient to cause operation of the instantaneous tripmechanism, but is nevertheless such that excess heatmay be generated inthe circuit, then a thermal means responsive to increased heat in thecircuit may be utilized for the purpose of automatically separating thecontacts in accordance with th aforementioned PT characteristic.

A further important object of the present in-. vention is to mount theinterposer which is automatically brought between the contacts by eitherof 'the means abovementioned in such a manner that it is always biasedtoward contact separating position so that in the event of failure ofthe mechanism, the automatically operated interposerwould be more likelyto move to a position separating the contacts than to any otherposition. I a

A further object of this invention includes the mounting of the manuallyoperated switch lever in such manner that it is yieldingly butpositively held in the open circuit or closed circuit position.

Still another object of this invention is to so a arrange the'insulating housing of the circuit breaker that it may be readily moldedby means of ordinary core dies without any other expensive molding orforming processes.

Still another and extremely important object or the present invention isthe arrangement of the housing of the combination switch and circuitbreaker, and thevarious parts thereof in such manner as readily tofacilitate assembly. That is, the housing is so formed and each of theparts is so formed that the parts may readily successively beplaced inthe housing from one side, the assembly operation requiring merely aseries of successive steps without any requirement for complicated toolsor complicated supporting and holding means for combining and supportingthe members during assembly.

A still further object of the present invention is to so arrange thehousing and each of the parts that when the cover plate is secured tothe housing at one side thereof, each of the .parts' is securely lockedin operative position.

"Many other objects and uses of the present invention will in part beapparent and in part pointed out inthe following description anddrawings. i which:

Figure 1 is an external view of the combination switchand circuitbreaker.

Figure 2 is an elevational view showing a plurality of the members ofFigure 1 mounted uponv a panel board. Figure 3 is a cross-sectional viewtaken on line 3-3 of Figure 2. I

Figure 9 ma view corresponding to Figure 8;. showing the automaticallyoperated interposer in tripped position.

Figure 10 is a cross-sectional view taken on line l0l 0 of Figure 4.

Figure 11 is a cross-sectional view taken on line li-ll of Figure 10.

Figure 12 is a cross-sectional view taken on line l2-I2 of Figure 4.

Figure 13 is a cross-sectional view taken on line l3-l3 of Figure 8.

Figure 14 is a cross-sectional view taken on line H-N of Figure 11.

Figure 15 is an exploded view of the combination switch and circuitbreaker showing the manually operated interposer in circuit breakingposition. Figure 16 is an exploded view of the combination switch andcircuit breaker showing the automatically operated interposer incircuitbreaking position.

trolling a series of branch or subsidiary circuits fed from a main lineor bus. The arrangement of the members of Figure 1 upon the panel boardas well as the arrangement of th various external portions. of theswitch and circuit breaker combination adapting it for use in panelboards will be more readily understood from a description of theinterior construction and relationship of the parts of the circuitbreaker itself.

The member of Figure 1 is shown in ordinary closed circuit positionwhich, when the cover plate is removed, corresponds to the arrangementshown in -Figure 5; while the arrangement shown in Figure4 shows theposition assumed by the parts when the manual operating handle 23 hasbeen moved to open circuit position.

As will readily be seen from Figures 4 and 5,

V the combination switch and circuit breaker com- Figure 4 is a sideview of the circuit breaker of Figure 1 with the cover plate removedand'with the contacts and various members arranged in open circuitposition.

Figure 5 corresponds to the view of Figure 4 showing the contacts andvarious members in ordinary closed circuit position. I

Figure 6 is a cross-sectional view taken on line turn conductivelyconnected to the solenoid coil 31. The solenoid coil 31, is connected bymeans 2,872,778 -of the integral connecting bar 38 to the movablecontact-carrying bar 39, the said contact-carrymovable contact surface4| from'the stationary contact surface 42 when the switch is'closed. Thestationary contact surface 42 is carried by the-stationary contactsupporting bar 43 (see to the opposite terminal or lead 45 into whichthe current is led from the bus bar.

It will thus be seen that when the circuit breaker is'so arranged thatone terminal 39 thereof is -Figures 13 and 16) which is in turnconnected- F by the angular lead-in bar 44 (Figures 4 and 16) connectedthrough the load to one pole of thecircuit and. the opposite terminal 45(connected.

any separation thereof, will result in an opening of the circuit. Suchseparation of the contacts may be accomplished either manually, wheneverit may be desired, orautomaticallyin response to faults or over currentconditions occurring in the circuit which the present circuit breaker isdesigned to protect.

For the purpose of separating contact surfaces 4| and 42 it may besuilicient merely to move the movable contact a sufficient distance awayfrom a stationary contact so that the air or gases between themfurnishes suflicient dielectric interposition to prevent effectively thepassage of current therebetween.

Where, owing to the fact that for panel board mounting of these circuitbreakers, the various dimensions thereof must be compressed as far aspossible and the amount of travel permissible in the movabl contacts isrelatively limited, then in order to effectively break the contactsapart so that no current may flow therebetween, the present inventionrelies not on a sufficient movement of the movable contact to accomplishthis purpose, but principally on the interposition of a physical barrierof dielectric material which either effectively serves to lengthen anypossible arcing path beyond the limits within which an arc may bemaintained for the particular current and pivoting portionBl as well asthe foot 52 are integrally molded from insulating material as a singleunit.

The interposer 50 securely attached to the foot 52 preferably is formedand pressed from a suitable insulating dielectric material to athickness facilitating interposition between a movable and stationarycontact. The central portion of the manual operating arm 23 comprises,as is more, particularly seen in Figures 4, and 16, a central opening orperforation 10 into which projects a knife edge I l, preferablyintegrally molded with the entire manual handle portion 23.

Owing to the fact that the handle 23 preferably is made of insulatingmaterial which may under appropriat circumstances possibly be brittie,the knife edge H is given a suihciently wide base so that in ordinaryoperation it will be adequately supported for the purposes hereinafterdescribed. The perforation H! in the manual handle member 23 and theknife edge ll thereof cooperate'to form a relatively frictionless play"less bearing for the handle 23 when the perforation 10 thereof ismounted over the supporting post or spindle l2.

The supporting post or spindle 12 preferably is of insulating materialintegrally molded as a voltage rating of the circuit breaker oreffectively servesto prevent any arcing path whatever.

Accordingly, for manually separating the contact when it is desired atselected intervals to disconnect the particular branch cirouit controll'i by the switch and circuit breaker combination, I prefer to utilizethe manually operated interposer (see particularly Figures 4, 5 and 15).The manually operated interposer 50 is so arranged as seen, in Figures 5and 4, that it may be readily moved from the position shown in Figure 5to the position shown in Figure 4, where it is interposed between thecontacts as is even more particularly seen in Figure 12.

The manually operated interposer 50 is connected by rivets SI, SI or inany other suitable manner to the foot 52 of the manual operating lever23. The manual operating lever as is more particularly seen in Figures4, 5 and 15, comprises a finger grasping portion 63, knurled to insure afirm grip, a foot 52 for supporting th barrier 50, and a centralpivoting portion 6|. Preferably the manual grasping portion 50 and thecentral the central portion SI of the manual operating 5 membercooperates with the remainder of the spindle 12, then the manualoperatinghandle' 23 may readily be rotated about the spindle withindefinite limits or stops. That is, the manual operating handle may berotated from the position shown in Figure 5 to the position shown inFigure 4; 'in each case the side of the knife edge approaching one ofthe surfaces of the cut-out'lii of the spindle.

During the actual rotation, the principal bearing surface between themanual o erating handle and the spindle is the knife edge H of themanual operating handle pressing into the angle 14 of the spindle. Thuseven though the perforation 10 of the manual operating handle isslightly larger in diameter than the greatest diameter of the spindle,nevertheless the pressure of the knifeedge ll of the handle into theangle 14 of the spindle furnishes an efiicient, play-less bearing.

The bearing herein is described as a playless one simply because it isnot a point-to-point contact between a point and an angle but a knifeedge-contact over an appreciable length with a corresponding angularmember; and such a knife edge contact over such appreciable lengthprevents any wobble or torque of such nature as to twist the handle outof a plane perpendicular to the axis of the spindle.

The finger grasping portion 60 of the manual operating handle 23projects through the slot in the upper surface 8| of the housing. Themovementof the manual operating handle 23 from the closed circuitposition shown in Figure 5 to the open circuit position shown in Figure4 is effectively limited by the shoulders 82 and 83 which lie at eitherend of the slot 80 and serve center and serves yieldingly to lock themanual I operating lever in place.

The compression spring 90 (Figures 4, 5 and which accomplishes thisfunction is mounted upon a slidable steel bar 9| which terminates at oneend thereof in a yoke or bearing surface 32. Theopposite end of the barat 93 projects through a perforation 94 in a suitable bearing plate 95,preferably of insulating material. The slidable steel bar is so arrangedthat the end 93 thereof may slide freely in the perforation 94 of thebearing plate 95. The yoke or bearing surface 92 of the steel bar 9|engages a notch 96 in the peripheral surface of the central portion ifof the manual operating arm 23.

'* The spring 90 is maintained under compression between the bearingplate 95 and the flanges of the yoke of bearing end of the steel bar 32.As may readily be seen in Figure 5, when the manual operating arm 23 isrotated into position where the interposer is not between the contactsand hence when the circuit breaker is in closed circuit position, thenthe effective pressure exerted by the compression spring 90 between thebearing plate 95 and the notch 92 is so directed beyond the center ofrotation of the manual operating lever 23 (the knife edge (I and angle14 engagement) as to exert a torque upon the manual operating lever 23tending to drive it even further in such direction as to swing theinterposer SKI-away from the contacts and to swing the finger graspingportion 80 thereof up against the stop 83.

When the manual operating lever 23 is rotatedv from the position shownin Figure 5 to the open circuit position shown in Figure 4 and theinterposer 50 is interposed between the contacts to produce the opencircuit position, then as will be noted by a comparison. of Figures 4and 5, the notch 92 of the central portion SI of the manual operatinglever 23 has been rotated to such position that the effective forcegenerated by the compression spring 90 is directed beyond the center ofrotation of the manual operating lever in an opposite directionfrom-that in which it was directed in the closed circuit position ofFigure, 5, thus tending to drive the finger grasping portion 60 of themanual operating arm 23 against the stop 82 and tending further todrive.interposer 50 into open circuit position.

Obviously the reason that the compressive force" of the spring 90 iseither in the open or in the closed position exerted in such directionas tomaintain the particular position ofthe switch (whether open orclosed) is that the axis of the spring is in each case shifted beyondthe center of rotation so that the effective direction of the forceexerted by the spring changes from a counterclockwise direction withrespect to Figure 5 to a clockwise rotation with respect to Figure 4about the center of rotation.

.A will be noted from a comparison of Figures 4 and 5,v the spring illis in aposition under greater compression and much less beyond centerwhen the switch is in the open circuit position of Figure 4 than whenthe switch is in the closed circuit position of Figure 5.

Accordingly, a positive closing action is provided for the closing ofthe switch, that is, it

requires only a slight movement of the finger grasping portion 50 of themanual operating lever 23 (when the circuit breaker is in the positionshown in Figure 4) to move the ,manual operating lever 23 .so that theforce exerted by the spring 90 passes through center and is exerted inan opposite sense to snap the manual operating arm 23 into closedcircuit position.

Thus, when the switch is in open circuit position, it requires merelyflicking of the finger grasping portion 60 of the manual operating lever23 to cause the interposer 50 to be snapped out of its position betweenthe movable .and stationary contact. Also for this reason, thepossibility that the contacts might-remain in bare proximity to eachother without actual complete removal of the interposer 50 is greatlyminimized since in the circuit opening position it is necessary for thecircuit opening movement to be substantially completed manually or elsethe manual operating lever 23 and the finger grasping portion 60 thereofwill immediately snap back to circuit closing position.

The position of the finger grasping portion 60 of the manual operatinglever 23 generally will indicate the on" or off condition of the switchunless the switch or circuit breaker has been automatically tripped openin which case other indicating means hereinafter described may beutilized.

In order that, upon the removal of the barrier 50, from the positionshown in Figure 4;;where it is between the movable and stationarycontact to the position shown inFigure 5 where it is no longer betweenthesecontacts, the movable contact should come into closed currentconducting contact with the stationary contact, I provide a leaf springI00 (Figures 4, 5 and 16) which tends to drive the movable contactsurface 4| (see-also Figure 13) down upon the stationary contact surface42. The. leaf spring fill] preferably is mounted upon a surface Hit" ofthe housing and secured thereto by a washer I02 and one of the rivets220 which serves to secure the cover plate 2| to the housing. In orderto insure that the leaf spring will be accurately positioned to exertproper contact pressure upon the movable contact, I provide a lug I03extending from the leaf Spring and registerable' with a recess I of thehousing which registry will serve adequately to prevent undue rotationof the leaf spring around the screw 22a.

The leaf spring I00 preferably is formed of any suitable elastic-metalpreferably of spring steel and is so arranged and bent as seenparticularly in the perspective exploded view of Figure 16 as, to exertpressure upon the contact-carrying arm 39 in such direction as to biasthe contact block '40 and the movable contact surface 4| thereof intoengagement with the stationary contact surface 42.

In orderfurther to .ensure that the movable contact-carrying arm 39cannot escape the pres- 79 sure, I prefer to shear the end H0 of theleaf tact surface 42.

as'raws bar from the leaf spring and vice versa.

Obviously a great deal of friction would be generated by the movement ofthe barrier 50 between the surfaces H and 42 of the contacts unless somefriction reducing means were provided. Such friction reducing means,however, must be of such a nature as not in any way to interfere withthe effective pressure between the two contacts when the circuit is tobe closed, while it must be readily usable to reduce the friction causedby I2I which is in turn mounted in the perforation I22 of the movablecontact block 40.

The stationary contact surface 42 projects somewhat as will be seen inFigure- 13, above the main portion of the stationary contact-carryingbar 43. In order to protect the Bakelite'houslng 20 from the effects ofany" momentary arcing that may occur during the instant o breaking ofthe contacts, an insulating plate of any suitable material I30 (seeparticularly Figures 8 and 13) is placed upon the inner side of thehousing and over the stationarycontact supporting members.

The insulating plate I30 has a perforation I2I therein which registerswith the stationary eon- The insulating plate also has.

first comes into contact with the wheel I in order to facilitate theraising of the wheel. However, ordinarily the interposer 50, although itis of suflicient thickness to provide for a sufficient dielectricbarrier between the contacts when it is in open circuit position andalthough it is of sufficient strength to permit it to separate thecontaots by the means herein described it is nevera perforation I32therein which provides a recess into which the wheel I20 may descend "sothat adequate pressure may be maintained between the contact surfaces 4iand 42. In order further to protect the housing 20 at I35 from anyarcing that might occur during the instant of opening of the circuit, anadditional small plate I30 of insulating material is placed beneath theperforation I32 effectively to protect the housing from any stray arcsthat might momentarily exist.

when the contacts are in closed circuit position, it will thus be notedby reference to Figure theless sufficiently thin so as to not make anysuch bevelling essential for the purpose of. lifting the movable contactwheel.

By this means, therefore, the contacts may be manually opened or closedfrom the outside of the housing by merely applying finger pressure inthe proper direction to the finger portion 00 of the manual operatinglever 25.

In the event of sudden overloads of great in tensity or in the event ofa sudden large drop in resistance, it becomes important immediately andautomatically to open the circuit, that is, to separate the movable andstationary contacts. Likewise, also, in the event of an overload of lessintensity or a drop in resistance below normal and sufficient to permitthe passage of current to such an'extent as to cause over-heating, meansare provided in thev present device for also separating the movable andstationary contacts andthereby opening the circuit at that point.

Both of such means, that is, the means responsive to suddenincreased'overloads and the means responsive to milder overloads whicheventually may be deleterious, are so arranged as to actuate theautomatically interposable barrier or interposer I50 (see particularlyFigures 8. and 9 as well as Figures 15, 4 and 5) The autowhichispreferably made of substantially the 13, that the contact surfaces 4|and 42 may come into close positive abutment in relation to each otherowing to the fact that the recess I32 in the to prevent friction betweenthe interposer and the contact surface.

' When the interposer slides between the contacts it, however, as willclearly be seen byv a compar son of Figures 4 and 5 with Figure 12,

first comes into contact with the freely rotatable wheel I20. Since thewheel is freely rotatable the barrier may readily slide thereunder andowing to the fact that the barrier is arranged so as to The depth of therecess is such as to provide allowance I for this additional movementduring the life of the breaker. The prime purpose of the'wheel is beunyieldingly mounted in its own plane, then the continued sliding of.the interposer 50 owing to manual or other pressure, will cause araising of the wheel I20'and a consequent raising of the movable contactblock 40 and of the movable contact surface 4 I, thus permitting theinterposer 50 to slide between the contacts.

In order to. facilitate this, the interposer 50 may be bevelled at theleading edge thereof which same dielectric material as the in'terposer50, a central portion III and a latch engaging arm I52.

The central or mounting portion I5I of ,the automatically interposableinterposer I50 is as is most clearly seen in Figures 8, 8 and 15,perforated at I53 to permit the mounting of the interposer I50 upon thespindle I2.

The spindle 12 has an increased diameter at I54 which is the baseportion thereof, most closely adjacent to the wall of the housing. Thecutoutportion I3 of the spindle -12 nevertheless extends into thislarger portion of the spindle and the angle I4 formed between thesurfaces of the cut-out portion also. etxends into the enlarged portionof the spindle. The enlargement of the spindle I2 at I54 permits notonly for a more secure connection between the spindle and, the

wall on which it is mounted but also serves to register and align thevarious members upon the spindle. That is, the perforation I50 of theautomatically interpo'sable member 150 is of a size permitting accurateregistry of the; perforation I53 with the large portion of the spindleI54, while the perforation I0 of the manual operating lever 23 is of asize registering with the narrower portion of the spindle I2.

Thus after the automatically interposable mem vber I50 has been placedupon the wider portion of thesplndle I54, the manual operating lever maybe placed thereon and by reason of the fact that the side thereof abutsagainst the surface portion I00 of the wider portion I54 of the spin-"dle, the manual operating lever cannot in any way interfere with theoperation of the automatically interposable interposer I50. This is moreparticularly so since the mounting portion I5I of the automaticallyinterposable member I58 is slightly narrower than the length of thewider portion I54 of the spindle I2 so that the mounting I5I may 'befree of contact with the, central mounting portion 8| oi the manualoperating lever 28.

The interposable barrier I50 is so arranged that it may be readilyrotated about the portion I54 of the spindle. For this purpose, anangular projection IGI is integrally extended from the body of themounting section I5I of the interposable member I50 into the perforationI53. The angu lar projection IBI registers with the angle '14 in thespindle and provides .a suitable bearing for the rotation of theautomatically interposable barrier I50.

Rotation of the automatically interposable member I50 about the spindleis also limited by the spacing of the walls of the spindle whichsurrounds the angular portion 14 thereof. That is, as seen in Figures 8and 9, a positive stop is provided in each direction of movement of theinterposer I50 by the abutment of the sides of the angular portion IS!against the walls of the spindle which join to form the angle I4thereof.

A compression spring I70 (Figure 8) is mounted on a steel slide bar I1I. The steel slide bar has a yoke or bearing surface I12 which at oneend thereof bears against a notch I13, of the automatically interposableinterposer I50. At the opposite end of the slide bar the bar is at tinserted in a perforation I'I5 of an insulating hear ing plate I15. Theend I" may slide freely in the perforation I15.

Compression spring I70 is under compression between the bearing plateI16 and the flanges ofthe end bearing I12 01 the steel slide bar I'Ii.As may be noted especially in connection with Figure 8, even when theautomatically interposable barrier I50 is not between the contacts'theaxis 01' the compression spring "0 is so arranged that the force exertedthereon is to the left of the center of rotation at I8I and hence is sodirected as to cause the interposer I50 to rotate in a. counterclockwisedirection with respect to Figure 8.

The interposer I50 is restrained from counterclockwise movement inresponse to the action of the metal bearing I80 and the latch I 8|there,

is no further restraint upon the rotation of the barrier I50 and sincethe action of the compression spring "0 is such as to immediatelyinitiate counterclockwise movement thereof with respect to Figure 8,then immediately upon such disengagement, the compression spring IIIlwill force the interposer I50 into the position shown in Figure 9 whereit extends between the movable and stationary contacts.

The open circuit position of the barrier I58 is definitely fixed by theabutment thereof against the-edge oi. the handle shutter 50 which thushalts continued rotation of the interposer I50 in response to the actionof the spring I'ID.

cult breaker. the interposer I50 will be positioned as shown in Figure 9directly between the movable and stationary contacts.

The abutment of the edges of the shutters in the tripped position formsa complete continuous seal between the contacts cutting oil any possibleeffective are path. Thus it may be seen by a comparison of Figures 8 and9 with Figures 4 and 5, that when the manually operated interposer 50 isin the closed circuit position of Figure 5, a free path is provided forthe descent of the automatically operated interposer I50 50 that it mayreadily move from the position shown in Figure 8'to the position shownin Figure 9 immediately upon release of the latch II of the trigger I82from its engagement with the metallic bearing surface I80 of the latchengaging portion I52 oi the interposer I50.

Therefore when by the operation of the manual operating lever 23, thebarrier is moved to closed circuit position, that is, to a positionwhere it no'longer extends between the movable contact and thestationary contact, no impediment of any kind exists to the automaticinterposition of the interposer I50 between these contacts in responseto a release of the latch engaging portion thereof I50 by the triggeri132.

Normally when no fault condition exists upon a line, the trigger I82 isso arranged that the latch portion i8I thereof engages the bearing I80of the interposer I50. For the purpose of retaining the interposer inthe desired non interposing position, the trigger I82 is spring biasedby means of spring 200 (Figures 10 and 11) into latching position.

The trigger I82 has a central mounting portion 20i which is perforatedat 202. An integral projection of the material of the trigger 203extends into the perforation 202 and terminates in a pointed angularportion 204 which provides a bearing for the trigger upon its shaft,permittin rotation thereof upon the shaft within predetermined limits.The mounting of the trigger. as is seen in Figures 10, 11 and 14comprises a spindle 2I0 preferably integrally formed from and se--"cured to the wall of the housing and having a By proper arrangementand spacing of the shutters (that is the closed circuit non-interposingposition of theshutter 50 and the open circuit interposingposition ofshutter I50) it is possible to ensure that m the tripped position of thecirnotch 2| I therein.

The angular point 200 of the trigger projects into the notch 2i I whichthus provides an angular bearing surface. The trigger I82 may thusrotate within predetermined limits on the spindle 2I0. A sleeve H2 ismounted on the spindle 2I0 and between the side of the trigger and theside of the cover plate, thus accurately positioning the trigger uponthe spindle. A hole in the spindle 2"! at 2I3 {Figure 10) permits oneend of the spring 200 to enter therethrough and engage a wall of thegroove or notch 2; the spring is wound about the sleeve, the other endat 2IB engaging the trigger I82.

The spring is so arranged that it exerts a rotative force upon thetrigger about the spindle 2I0 in a counterclockwise direction withrespect t Figure 9 and hence tends to bias the trigger I82 so that thelatch portion I8I thereof is positively .in engagement with the metallicbearing I of the latch engaging portion I52 of the interposer elementswhich respond mechanically to variations in the amount of current.

Trigger release arm 220 is so arranged as to cooperate with the member245 of the solenoid assembly 230 in the manner shown in Figures 4, 5, 8and 9. As has been above noted, the solenoid is in the current paththrough the movable and stationary contacts. Thus, with respect toFigure 4, the current enters at the connecting lug or terminal 45,passes through the contact blocks and the members 39 and 38 into thecoils 31 of the solenoid and thence through the wire'braid 85, thethermal element 34 and the lug 33 and bar 32 into the opposite terminal30.

The solenoid coil 31 is composed of several turns of conducting materialwhich, in the preferred embodiment of'the present invention, is

'square copper of substantial cross-section. The

large cross-sectional areaiminimizes the resistance which is injectedinto the circuit and also increases the actual physical strength of thecoil, thus making it possible to use an integral extension 3M9 of thesolenoid coil itself as the lead in and physical support for the movablecontact block.

It will be noted -that the contact engaging spring I forces the contactmember 40 toward the molded wall of the housing. The point of engagementof this spring with the bar 38 is between the contact and the coil. Thespring thus produces reactions at each end of the bar 38-49: one,producing contact engaging pressure when the interposers are retracted;the other maintaining the solenoid assembly in its sockets.

To obviate .the necessity for insulation on the solenoid, the coilpreferably is wound. with a reasonably large air space between theturns. The solenoid coil 31 as is seen in Figures 4, 5, 8,

and}? is mounted on an insulating sleeve 23I which prevents any'currentleakage between the successive turns of the coil and at the same timeserves to insulate the coil from other members of the mechanism.

The insulating sleeve 23! may be secured with- I in the housing in anysuitable manner. Thus one end thereof may at 232 be supported in adepression of the bottom wall of the housing and the opposite endthereof may be supported in a U-shaped member 233 preferably integrallymolded from a wall of the housing.

For purposes of securing the support of the sleeve 23I at 232 in thehousing, a steel core 234 having a flange 235 engaging the sleeve may besecured at the bottom of the sleeve to provide a suitable bearing forthe main armature spring and further to rigidify and strengthen thesleeve against any stresses that may be placed thereon.

The movable solenoid armature 240 is slidably.

mounted in the top of the sleeve 23I'and preferably may be maintained inthe normal raised position shown in Figure 8 by the compression spring 2which is placed between the base of the -movable armature and the top ofthe stationary core. Since the slidable armature 240 is preferably madeof steel or any other suitable magnetizable material, it may be drawndown so that it extends substantially within the coils 31. of thesolenoid when a suiilcient current is passed through such coils.

Spring 2 of the solenoid should be so calibrated and arranged that itwill permit the drawing of the armature 240 within e coils of thesolenoid in response only to an ove oad sumciently excessive to possiblycause damage. That is, the spring I should not permit descent of thesolenoid armature 240 when ordinary currents customarily to be expectedin the circuit are passing through the coil 31. Nor should it evenpermit descent of the armature when only slightly excessive currents arepassing through the coil. But the movement of the armature 240 into thecoil should be in response only to excessive loads.

The circular cross-section of the armature 240 and the free, fit thereofwithin the sleeve 23I permits it to slide readily. A rectangular triggerarm engaging member 245 is secured either by welding or by any othersuitable means to the top of the armature. Figure 15, the trigger armengaging member 245 is squared-off and preferably the interior wall 245(Figure 9) is close to the plate 245 of the armature (see also Figure6).

As is therefore seen particularly in Figure 6, while the squaring-off ofthe plate 245 does not interfere with the rise or fall of the armature,it prevents undue rotation of the armature to ensure that the triggerarm engaging portion thereof will always extend in such a direction asto engage the trigger and to ensure that it will not rotate out ofengagement with the trigger.

The slots 241 (Figure 16) cut into the armature 2M and magnet 234 andthe slot 248 out into the trigger arm engaging plate 245 serve toprevent eddy currents which might otherwise tend to reduce the totalmagnetic flux in the circuit 'or occasion any loss of energy owing toheating.

When an overload occurs for any reason causing an excessive current topass through the coil 31 of the solenoid, then the armature 240 isattracted into the coil of the solenoid, the plat 245 engages thetrigger arm 220, presses the arm downwardly with respect to Figure 9,causes a rotation of the trigger about the spindle 2I0 in a .directionopposite to that in which the trigger was originally biased by thetrigger spring 200, causes a movement of the latch portion I8l there ofout of engagement with the bearing I80 of the latch engaging arm I52 ofthe interposer I50 0 and" thus removes any restraint upon the rotaf tionof the interposer I50, thereby permitting the compression spring I todrive the interposer from the position shown in Figure 9, where theinterposer I as will now be clearly understood,

W extends between the movable and stationary contacts.

nbviously, any such tripping of the interposer I50 into circuit openingposition shown in Figure 9 will not occur owing to the energization ofthe 6-: solenoid 230 unless the movable and stationary contacts arepressed together, that is, unles the entire mechanism has first beenplaced in the position shown in Figure 5 where the manually operatedinterposer 50 is no longer between them.

As will be noted in Figure 5, when the manual- 1y operated interposer I0is moved from the open circuit position of Figure 4 to the closedcircuit.

position of Figure 5then' not only does it permit the circuit to beclosed between the movable and stationary contacts but also it is movedto a position where it will not interfere with the descent of theautomatically operated interposer upon release of its latch engaging armI52. So that when the automatically operated interposer I50 moves fromthe position shown in Figures 5 and 8 into the position shown in Figure9, in response to over current conditions, 'it-is-clearly free to do sowithout interfering with the interposer 50.

Obviously when the interposer I50 moves from the position shown inFigures 5 and 8 to the Preferably as is seen in position shown in Figure9, it engages and raises the wheel I20 and separates the stationary andmovable contacts in exactly the same manner as has been shown heretoforein the manually op-'- erated interposer 50. The manually operatedinterposer 50 is off-set out of the principal plane of the main portionof the manual operating lever 23 so that it will be coplanar withthe-automatically operated interposer I50.

This condition simplifies the resetting process when the automaticallyoperated interposer I50 to its original position preparatory to latchingengagement with the arm I52 of the interposer I50. Since the interposer50 and the interposer I50 are coplanar with respect to each other,itwill i be then clear that the movement of the manual operating lever 23from the closed circuit position shown in Figure to the open circuitposition shown in' Figure 4 will result in a corresponding movement ofthe interposer 50 as shown and will also therefore result in the pushingup of the interposer I50 by the interposer 50,

despite the force of the spring. In such later case, spring 24I will notbe necessary. v

Ihave here shown, however, the preferred embodiment wherein compressionspring I which may readily be calibrated is utilized to resist the forceexerted upon the armature by the passage ofcurrent through the solenoid.By this means, the automatically operated interposer I59 may be trippedin response to a' specific excessive overload of substantial extent; Itmay be necessary or desirable to effect a similar tripping operation ofthe interposer I50when an overload which is not greatly excessive but'isnevertheless continuous occurs.

In order to accomplish this purpose, I provide a thermal bi-metallicelement 34 (Figures 4. 5, 8 and 9) which is responsive to heatingeifects. which may occur in this circuit. The thermal -bi-metallicelement 34 is so arranged that the lower end thereof will be rotatedclockwise with respect to Figure 8 under the influence of heat. Thecurrent path from the connecting lug through the contacts and to theconnectin lug When the manually operated interposerf has been moved intoposition shown in Figure 4. it

will have raised the automatically operated interposer I50 so that thelatch engaging arm I52 will be in latchin engagement with the latch I8Iof the trigger I 82. And the circuit breaker will havebeen restored toits original non-tripped position but the circuit will then remain opensince in the very operation of resetting the 'interposer I50, theinterposler 50 has been moved into position between the contacts.

Subsequent to this operation which thus results in the position of themembers shown in Figure 4, in order to restore the circuit, the manuallyoperableinterposer 50 must be moved back to the position shown in Figure5.- If, during such movement, and at the moment the mov able contacttouches the stationary contact, over current conditions still exist onthe l ne. thenthe solenoid coil 31 will be immediately energized to tripthe automatically interposable barrier I50 to tripped position. I

It is thus absolutely impossible to 110171 the circuitf closed when overcurrent conditions exist on the line and to this extent at least thepresent invention isa. trip-free circuit breaker. In other words, thetripping action which results in the placement of the interposerI50between the movable and stationary contacts occurs independently ofthe manual operated lever 23.

The spring 200 wh ch biases the trigger I02 in the proper positionshould preferably be only oi sufllcient strength for this purpose.Otherwise it will be necessary not merely to calibrate the spring 2 ofthe solenoid in accordance with the particular overload currentconditions which are to be expected but also to calibrate the spring200, in accordancetherewith.

It will also be possible, should it be desirable. merely to depend onthe spring 200 of the trigger and to arrange this spring so that it willpermit a release of the latch only when a suillcient force is exertedupon the armature to rotate the trigger 30 is through the thermalelement 34. Thus the currentis led from connecting lug 45 through thebar 44 to the contact surfaces 42 and 4|, the contact supporting arm 39and 38, the. solenoid coil 31, the wire braid 35 to the thermal element;from the thermal element, the current flows into the thermal elementsupporting arm 33, thence through the bar 32 to the opposite connectingter minal 30. V

Any overload conditions on the line which may result in the passage ofsuflicient current to generate heat in the circuit but which may not beof suilicient intensity to energize the solenoid 230 may nevertheless besufiicient' to. cause 'a bending of th thermal element 34. The thermalelement 34 preferably is so calibrated that it will bend into engagementwith the arm 22: of the f trigger under predetermined excessive load"conditions which are not greatly in excess of the desired currentcondition but which nevertheless resuit in the generation of excessiveheat.

Upon the bending of the thermal element 34 in response to such heatingconditions in the circuit,

the end thereof will be swung over in the manner shown in the dotted.lines of Figure 5 into mechanical contact with. the trigger arm 22I andwill cause a. rotation of the trigger I82 about the spindle 2| 0, suchrotation releasing the latch portion I!" thereof from the metallicbearing I80 of the latch engaging arm I52 of the automaticallyinterposable interposer I50.

This permits a tripping operation to occur and I permits the compressionspring I10 to force the automatically operated interposer I50 into theposition shown in Figure 9. i

The automatically operated interposer may then be reset in the mannerabove described by the operation of the manual operating lever 23, butthe trigger I82jwill not be rotated to latching position by its spring200 until the heating conditions which resulted in a, curling of thethermal element 34 have been removed.

Thus, should .the'interposer I50 be reset in the manner above describedimmediately after tripping in response .to heating conditions, it willimmediately trip once more'owing to the fact that the thermal elementwill not have had an opportunity tocool off sumcientlyto permit it todisengage the trigger arm 22 I. For this reason,

. therefore, the interposer I 50 cannot be reset until whatever heat hasalready been generated in the circuit has'had an-opportunity to radiateaway.-

' broken.

cessive overload occur, the solenoid operating mechanism 230 will causeanother tripping; and should there be' in the case of such resetting aslight overload resulting in the generation'of heat once more, thenafter heat has been generated for a sufficient amount of time to permitthe curling over of the thermal element 34, the interposer I50 willagain be tripped and the circuit In every case it must beunderstood'that the operation of the interposer I50 is completely freeof the manual operating-arm 23 and that it is absolutely impossible tomaintain thecircuit in closed circuit position when fault conditionsexist upon the line.

The circuit breaker may be adjusted for different types of excessiveoverloads by proper calibration, and interchanging of the spring 2, andit may be adjusted for different responses to slight or heatingoverloads=by either a change in the bi-metallie elementor a shifting ofthe bi-metallic element 34 with respect to the trigger arm 2 2I so as torequire a diiference in the amount of bending of the thermal elementbefore it is in mechanical contact with-the trigger arm 22I.

In order to provide for such shifting of position I provide that a screw210 be threaded through the arm 33 which supports the thermal element344and that the end of this screw bear- 300 and extending as is shown inFigure 9 im mediately below the latch engaging arm I52 of the interposerI50.

A spring303 (Figure 9) is at one end thereof engaged in an opening 301of the automatically operated interposer I50 and at the other end at 308is caught beneath the finger 305. The central coil portion thereof iswound about the shaft I2 ing against the ledge 2H in the interior of vthe housing. The arm 33 is made of resilientconductive material and issufficiently elastic so that upon rotation of the screw 210 the arm33will be moved closerto or further away from the ledge 2II thuschanging the position of the mounting of the thermal element 34 andshifting it closer to or further away from the trigger arm The mountingportion 8| of the manual operating lever 23 is so arranged-that whateverthe position of the manual operating lever, whether on or oil, the slot80 is completely covered over so that virtually no dust may enter fromthe outside into the mechanism.

This results, however, in making it either difficult or impossible toexamine the interior of the mechanism while the circuit breaker ismounted upon the panel board to determine whether the circuit breakerhas been tripped. As a matter of fact, even though the finger graspingportion 80 of the manually operated lever 23 is in the closed circuitposition shown in Figure 5,- the circuit breaker may be tripped open bythe dropping of the interposer I to the position shown in Figure 9without changing the position of the finger grasping portion 80. Thusunless some outward visual indication is provided as to the position ofthe interposer I50, it will be difficult if not impossible to determinewhether a circuit breaker hasbeen tripped.

Accordingly, I have provided a visual indicator which will readily showthe position of the .automatically operated interposer I50. The visualindicator is preferably a fiat metallic member 300 (Figures 5 and 16)carrying a flag "I and having a perforation 302 registerable with themounting shaft 12 and an angular projection 303 registerable with theangle 14 of the mounting shaft. The indicator 300 is mounted upon theshaft 12 above the interposer I50 and the mounting portion SI of themanually operated lever 23. The indicator disk 300 also has a finger 305preferably at right angles to the main portion of the disk and is placedbetween the automatic interposer I50 and the manual operating armmounting CI. The spring 306 and especially the, end 303 thereof istherefore biased to raise the'iinger 305 and thus is biased in such adirection as to cause a. rotation of the disk 300 so as to raise theflag 30I. Normally, however, when the automatically operated interposerI50 is in the latched position shown in Figure 8, the latch engaging'armI52 thereof presses down the finger 305 against the bias of the end 303of the spring and hence also presses down the flag 30l so that it is notvisible. .When theautomatically operated interposer I50 is tripped intothe position shown in Figure 9 and the latch engaging portion I52thereof is raised, then the end 308 of the spring pushes up the finger305 of the indicator and pushes the flag 30I upinto the slot 30 where itmay be visible from the outside alongside the mounting portion SI of themanual operating lever 23.

Accordingly, even though the finger grasping portion 60 of themanualoperating lever 23 is in the apparent closed circuit position, theappearance of the flag 30I in the slot alongside the mounting portion 6|of the manual operating lever will immediately give an indication thatthe circuit breaker has been tripped to open circuit positions 1 Inorder to provide a recess in the mounting portion 5| to permit the flag301 to appear in the slot 80, the mounting portion SI is cut out at theflag 30! therein (3l0, Figure 5).

In order to prevent any possibility during the,

opening of the contacts of any arcing over between the movable contactblock 40 and the bar 44, I prefer to provide insulatin barriers 320 and32I (Figure 5) which may be mounted in notch 322 of the ledge or boss323 in the bottom wall of the housing and in notches 324 and 325 of anend wall of the housing.

In order further to protect the members against arcing, I provide anupper shield 340 (see Figures 5 and 16) having a T-shaped opening 3therein to permit the engagement of the contacts and the passage. of thewheel therethrough. This protective shield may be formed or stamped toshape, the shape being, of course, determined by the contour of thehousing and obviously this shield 340 is spaced from the bottom shieldI30 by a distance sufllcient to permit the free passage of theinsulating interposers between them.

From the foregoing description it will be seen that each of the membersof the circuit breaker is supported within the housing in such a mannerthat they may readily be assembled in connection therewith. The housingitself is so formed and constructed as to provide supporting elements ofvarious types, most of which having hereinbefore been described. Thus,for instance, the bar 32 which is an extension of the connect ing lug 30is securely mounted within the housing assembly by the screw 360(Figures 4 and 5) which passes through a lug 36I of the bar 32 and intoan integrally molded rectangular support 363 of the housing. The bar 32is also securely positioned within the housing by being M0 to a depthsumcient to permit the entry of mounted between the rectangular abutment308 and the angular portion 884 of the housing.

Each of the interposers and the manual operating lever rotates about asingle spindle which is integrally molded from or secured to one wall ofthe housing.

The member 44 which carries the lug 45 is also securely mounted withinthe housing, as is seenin Figure 9, by being mounted in a recess orchannel 388 thereof. The various portions of the housing cooperate withother elements to provide stops for certain of the movements and toprovide moun'tings and securement in the manner hereinbefore described.When the cover plate 2| is secured in place by the rivets 22, then eachof the members is securely fixed in its operative position, particularlyas is seen by the cross-sec tional view of Figure 6. e Thus, the finalsecurement of all of the members isobtained after most of the membershave merely been slipped into place by the attachment of the covermember II andthe passing of the rivets '22 through the elements and thehousing.

Obviously, suitable on-oi! indication may be printed or written on theoutside of the housing in cooperation with the manual operating lever 23and particularl the lingo:- graspi portion I50. I! so desired themounted portion 6| of the manual operatinglever may be lettered with thelegend "off" at 310 (Figure 4) and with the legend on at "I (Figure 5).Furthermore the indentation 312 of the mounted portion 0! of the manualoperating lever 23 may be provided and may be suitably colored toindicate the -on" pomtion, since it will be visible only when the fingergrasping portion of the manual operating lever 23 has been moved to theon position. From the foregoing description of the various elements andthe manner in which they operate, it will be clear that the same type ofapparatus may be adapted, where desired, to multi-pole operation andwhere desired, it may be possible to place two or more of thecombination switch and circuit breakers side by side for multi-poleoperation connecting the manual operating levers 20 by passing anysuitable member through the perforation 380 (Figure 4) of adjoiningmanual op erating levers so that multi-pol switching may As has beenabove-emphasized, while this circuit breaker is useful for individualoperation, the greatest utility lies in its arrangement and adaptabilityfor panel board mounting in .th manner shown in Figure 2. l i

The lead connecting lug 30 as will be noted 55 particularly withreference to Figure 4 is protected by the curved extension 390 of thehousing and is enclosed between the cover plate and this extension. Thelead 45 may, ifdesired. extend from the opposite side or it may wherenecessary be protected in a similar manner by the extension 395 of thecover plate (Figure 1) and/or by a corresponding extension of thehousing; For ordinary panel board mounting where the lead 40 is to beused as part of the support for :the

circuit breaker upon the bus it may be desirable ers of the presentinvention are shown mounted upon a panel board with the leads 45connected by suitable conductive securing means, as for instance thescrews 391, to a common bus 398,

s and the opposit leads connected to load wires 380 in any suitablemanner. The leads 45 obviously may be sufiicient to provide adequatesupport for one end of the circuit breaker upon the common bus 308,although if desired any other securing means may be provided for thispurpose, as for instance, the foot or lug 400 which may serve to engagea suitable clamp member upon the suppbrting base 401 of the panel orwhich may be extended and formed in such a manner as to provide a screwengaging means. As seen in Figure 3, flanged plate 400a may be screwedto 'thepanel and may be formed to encase foot or lug 400 to secure thesame to the panel.

The foot 402 may be provided at 'the opposite end of the circuit breakerin order to Both of the lugs or feet 400 and 402 are, asseen in thefigures, integral with the molded casing.

foot 402 may be provided with an open ended slot 403', thewalls of whichare oriented in planes parallel to the end walls of the housing; and arecess 404' may be provided in the-upper surface of the foot 402extending from the side opposite the open end of the slot to a pointbeyond the closed end of the slot for positioning the head of screw 403.

In order to insure that the circuit breaker will be perfectly level upon.the panel board support 40l, the foot 402 may be flush with theundersurface of the circuit breaker or, if this is not 40 feasible, thenan additional support 405 maybe twill thus be through the common busj98to the connecting lead through the circuit, breaker andthe' oppositelead 30' (Figure 4) and 'therefrom to the load wire 099 (Figure 3) tothe mechstance to the terminal block 420 to which is connected thereturn wires from the individual loads: the termina block 420 beingconnected to the side of-the lin opposite that to which thecommonbusisconnected.

Each of the individual circuits operated from each of the individualcircuit breakers is thus fully'protected by its own individual circuitbreaker while theentire panel board and all of the elements operatedtherefrom may, if desired. e protected by a single circuit breakercapable of handling the iull load. The panel which the panel boardsupporting member 401 is secured in anysuitable manner. The main baseand mounting portion 410 may have side membersl'i'l and covering flanges2. The covering flanges 4|! may be formed in order to support a slottedframe covering member 413:: which willconceal all of the circuitbreakers except for the toi surfaces thereof at 414, 4 from which thelinger grasping P rtion of the manual operating lever 20 projects. j

In this manner no part of the circuit breakers or of the panel board orof the connecting wires As may readily be seen in Figures 6 and 7, the

anism, and then 'any suitable return, as for inthe circuit; breakers arethus to be mounted closely adjacent to each other, the ends of rivets 22may be countersunk in the molding (and bossesplaced thereabout) toprovide an airspace between said rivet ends so that they will not be incontact with similar rivet ends on adjacent breakers. The rivet ends onadjacent breakers The thermal tripping means which acts in response toan overload which is not greatly excessive, but nevertheless isexcessive, is slowly heated as this minor overload continues until iteffects the tripping operation above described. As the overloadincreases the thermal element acts more and more rapidly. However,should excessive over-loads occur, then it may be danmay'then extendshghtly into the counterbore.

Such adjacent rivet ends are the ones extending from the cover plate.The cover plate is a die cut blank and the head of the rivet engages thecover plate at the rivet openings, while the op-' posite ends of therivets in the counterbores or recesses of the molding are spun down.

Where only a thermal trip is desired without changing the structure ofthe device, then the core of the solenoid coil may be removed or member245 of the core may be removed, thus leaving a dummy solenoid bushingand coil; in such case, only the thermal trip will operate. In this casealso, the coil arrangement may be dispensed with,

and the braid 36 from the thermal element may be connected to a metallictube or other pivotable element which may carry the movable contact arm.Such tube or pivotable element may rotate about an insulating tubesimilar to the insulating tube 23! of the solenoid.

The present circuit breaker is comprised'o'f a magnetic trip and athermal time delay element may be incorporated in the usual form ofpower and light panel to handle branch circuits- The members as has beennoted are readily mounted in any suitable support upon the panel andrequire no more space than a fused switch, and, taking intoconsideration the expense or replacement of fuses and the expense ofoperation of the fused switch, they are better than an ade-- quatesubstitute therefor.

They are designed to be mounted in a panel with a number of units sideby side with the line terminal of each circuit breaker screwed directlyto the common bus, this screw also serving to hold one end of the unitmechanically, the opposite end of the circuit breaker being mechanicallysupported in any suitable manner. In this manner therefore anyindividual units may be removed and replaced without disturbing adjoininunits.

As has been above noted the circuit breaker of the present invention istrip free in that it will open even though the handle is held in closedposition and the switch cannot be held against overload or shortcircuit. The only way in which the circuit breaker may be reset afterthe interposer has been tripped is by moving the manually interposableinterposer between contacts and thus maintaining the contacts in opencircuit position. Should the circuit protected by the circuit breakerstill be under overload conditions, then permitting the manuallyinterposable interposer to be moved away from between the contacts willagain cause the actuation of the thermal and/or solenoid elements tocause the automatically interposable interposer to move hetweenthecontacts and thus maintain the separation therebetween.

The circuit breaker, as has been noted, trips immediately upon anexcessive overload owing to the operation of solenoid means abovedescribed.

gerous to allow any delay until the thermal element is sufficientlyheated to accomplish the tripping operation and accordingly the solenoidtripping mechanism acts instantaneously upon greatly excessiveoverloads.

- Furthermore, the ability of the present circuit breaker to trip athigh speed upon greatly excessive overloads would serve to prevent themain protecting circuit breaker from tripping upon the occurrence of anexcessiv overload in a single branch circuit, and thus "will serve toprevent the other branch circuits operating from the same bus from beingdisconnected from the main circuit. a

In the foregoing description, cooperating'elements have been set forthand the interrelation therebetween has been described.

Various modifications and changes in the different parts will now beobvious to those skilled in the art. Accordingly, it is desired to bebound not by the specific disclosures herein but only by the appendedclaims. Y

This application is filed simultaneously with the application of FrankJ. Pokorny, Serial No. 331,984, for Circuit breaker, now Patent No.2,319,262, issued May 18, 1943; the application of William M. Scott,Jr., Serial No. 332,037, for

Circuit breaker, no-w Patent No. 2,303,959, issued December 1, 1942; andthe application of Otto Jensen, Serial No. 331,967, for Circuit breaker,

now Patent No. 2,321,603, issued June 15, 1943.

In this application I have claimed those inventions and portions of thestructure devised by. me.

I claim:

1. A circuit interrupter structure, a molded casing for enclosing andsupporting the parts thereof, said molded casing having a side wall andother walls and members extending perpendicularly thereto, means at oneend of said circuit interrupter structure for supporting said end upon apanel, and a lug integral with the molded casing extending from theother end of said casing, said lug extending from said casing and beyondthe boundaries of the structure at a corner thereof and having an openended slot tocooperate with a mounting means for securing said other endof the circuit interrupter to the panel, the walls of said slot beingarranged in planes normal to the plane of said side walls.

2. A circuit interrupter structure, a molded casing for enclosing andsupporting the parts thereof, said molded casing having a side wall andother walls and members extending perpendicularly thereto, means at oneend of said circult interrupter structure for supporting said end upon apanel, and 9. lug integral with the molded casing extending from theother end of said oasing, said lug extending from said casing and beyondthe boundaries of the structure at a corner thereof and having an openended slot to cooperate with a mounting means for securing said otherend of the circuit interrupter to the panel, the walls of said slotbeing oriented in planes parallel to the planes of certain of said otherwalls and members, and a recess in said lug in a surface thereof andextending from a side opposite the open end of said slot, and extendingin angularly adjacent to said open side, the said end wallsoieach-circuit breakerextending in the same plane, said cover plateextending beyond said end wall a greater distance than said terminal,said extensions of said cover plates forming interpolar barriers betweenadjacent similar terminals in adjacent cimmtinterrupters.

4. Ina circuit interrupter, a molded casing imenclosing and supportingthe parts thereof; said casing having an open side, and a cover plateand beyond the -end said terminal and an integral extension 0! saidcover plate beyond said end wall and beyond the end of said terminal,

said extensions forming insulating guards for said terminal. I

6. A circuit breaker to be mounted on a panel inclose adjacency to othersimilar circuit breakfor said open side; a terminal extended from anend'wall of said casing, said end wall being angularly adjacent to saidopen side, said cover plate extending beyond said end wall a greaterdistance than said terminal, said extension of said cover plate beyondsaid end wall being removablewhile said cover plate is in securedposition over said open side oi said casing,

5. A circuitinterrupter and a molded casing 'therefor, said casinghaving a side wall, an opers, a molded housing having a side wall, anopposed open side and a cover thereioryrivets passing through said sidewall and said cover for securing said cover in place and for cooperatingin supporting members-oi the circuit breaker, the headset said rivetsbeing countersunk in a counterbore in said side wall, the heads ofrivets on the adjacent circuit breaker being nested in said counterborewith an air space between adjacent rivet heads, and bosses on said sidewall around said oounterbores to increase said air space.

'I. A circuit breaker to be mounted on a panel in close'adjacency toother similar circuit breakers, a molded housing having a sidewall, anopposed open side and a cover therefor; rivets passing through said sidewall and said cover for securing said cover in place and for cooperatingin supporting membersoi the circuit'breaker, and means for spacing saidcircuit breaker from an adjacent circuit breaker moimted on said panel,said means comprising bosses on said.side wall projecting therefrom andarranged to come into contact with a side oi said adjacent circuitbreaker.

HERBERT C. GRAVES, Ja.

